1. Field of the Invention
The present general inventive concept relates to an ink jet head and a method of fabricating the same, and more particularly, to an ink jet head including a metal chamber layer and a method of fabricating the same.
2. Description of the Related Art
An ink jet recording device functions to print an image by ejecting fine droplets of printing ink to a desired position on a recording medium. Ink jet recording devices have been widely used due to their inexpensive price and characteristics capable of printing numerous colors at a high resolution. The ink jet recording device includes an ink jet head for actually ejecting ink and an ink container in fluid communication with the ink jet head. The ink stored in the ink container is supplied into the ink jet head through an ink-feed passage, and the ink jet head ejects the ink supplied from the ink container to the recording medium to perform a printing operation.
A process of fabricating the ink jet head may be classified as a hybrid type or a monolithic type depending upon a method of forming a chamber layer and a nozzle layer of the ink jet head. According to the hybrid type the chamber layer and the nozzle layer having nozzles for ejecting ink are separately formed on a substrate having pressure generating elements thereon. The nozzle layer may be adhered to the chamber layer to fabricate the ink jet head. However, misalignment may occur between the pressure-generating elements and the nozzles during the process of adhering the nozzle layer to the chamber layer. In addition, the process may be complicated, since the chamber layer and the nozzle layer are manufactured through separate processes. On the other hand, a method of fabricating the ink jet head in accordance with the monolithic type can create the chamber layer and the nozzle layer such that the nozzles are precisely aligned with the pressure generating elements. In addition, the monolithic type is capable of decreasing a manufacturing cost and improving productivity by virtue of simplifying the manufacturing process by forming the chamber layer and the nozzle layer by the same process. Examples of methods of fabricating the ink jet head in accordance with the monolithic type are disclosed in U.S. Pat. Nos. 5,478,606, 5,524,784, and 6,022,482.
FIGS. 1 to 4 are cross-sectional views illustrating a method of fabricating a conventional monolithic type ink jet head.
Referring to FIG. 1, heat-generating resistors 102 for generating pressure for ink ejection are formed on a substrate 100. An insulating passivation layer 104 is formed on an entire surface of the substrate having the heat-generating resistors 102 thereon. Next, a chamber layer 106 defining sidewalls of an ink flow path is formed on the insulating passivation layer 104. The chamber layer 106 is conventionally formed of a negative photosensitive resin layer.
Referring to FIG. 2, a sacrificial material layer 108 is formed on the substrate 100 having the chamber layer 106 thereon. The sacrificial material layer 108 is formed of a soluble resin layer such as a positive photoresist. The sacrificial material layer 108 is then polished by a chemical mechanical polishing (CMP) method.
Referring to FIG. 3, as a result of performing the CMP process, a sacrificial layer 108′ is formed between the sidewalls defined by the chamber layer 106 to cover a region where the ink flow path is to be formed. The sacrificial layer 108′ is provided as a supporting layer for the nozzle layer to be formed by the following processes.
Referring to FIG. 4, a resin layer is formed on the chamber layer 106 and the sacrificial layer 108′. The resin layer is patterned to form the nozzle layer 112 having nozzles 112′ corresponding to the heat-generating resistors 102, respectively. Then, the substrate 100 is etched to form an ink-feed passage 114, and the sacrificial layer 108′ is then removed.
A height of the ink flow path is affected by a thickness of the chamber layer 106. Therefore, the thickness of the chamber layer 106 should be adjustable and precisely reproducible. In a method of fabricating the conventional monolithic ink jet head, in order to create the chamber layer 106 having a reproducible thickness, the chamber layer 106 is formed of a material layer having a polish selectivity (polishing rate of the sacrificial layer/polishing rate of the chamber layer) with respect to the sacrificial layer 108. In this case, the chamber layer 106 functions as a polish stop layer for detecting a polishing stop point of the CMP process. However, as described above, when both the chamber layer 106 and the sacrificial material layer 108 are formed of a resin material, it may be difficult to make the chamber layer 106 have a polish selectivity with respect to the sacrificial material layer 108. As a result, the chamber layer 106 does not function as the polish stop layer and is polished together with the sacrificial material layer 108, thereby making it difficult to adjust and precisely reproduce the thickness of the chamber layer 106. Additionally, although the sacrificial layer 108′ may be formed by applying and patterning the positive photoresist without employing the above-mentioned CMP process, it may be difficult to form the sacrificial layer 108′ having a flat top surface due to a step between the sacrificial material layer 108 and the chamber layer 106. This may make it difficult to form the ink flow path having uniform dimensions.